CQRS Pattern

Command Query Responsibility Segregation implementation.

Commands

Commands modify state and return Result.

Interfaces

Interface	Description
ICommand<TResponse>	Command with response
ICommand	Command returning Result
ICommandHandler<TCommand, TResponse>	Handler interface
ICommandHandler<TCommand>	Handler for Result commands

Usage

public record CreateUserCommand(string Email, string Name) : ICommand<Guid>;

public class CreateUserCommandHandler : ICommandHandler<CreateUserCommand, Guid> { public async Task<Result<Guid>> Handle(CreateUserCommand request, CancellationToken ct) { var user = new User(request.Email, request.Name); await _repo.AddAsync(user, ct); return Result<Guid>.Success(user.Id); } }

Queries

Queries read state without side effects.

Interfaces

Interface	Description
IQuery<TResponse>	Query with response
IQueryHandler<TQuery, TResponse>	Handler interface

Usage

public record GetUserByIdQuery(Guid Id) : IQuery<UserDto?>;

public class GetUserByIdQueryHandler : IQueryHandler<GetUserByIdQuery, UserDto?> { public async Task<UserDto?> Handle(GetUserByIdQuery request, CancellationToken ct) { return await _repo.GetByIdAsync(request.Id, ct); } }